heres my idea (im a bit of a kitbasher, so my mind is always thinking of things like this)
basically, the on-comming train trips the trigger at the same time it trips the bridge mechanism, so that the cars will be allowed to proceed when the bridge is lowered


basically, the on-comming train trips the trigger at the same time it trips the bridge mechanism, so that the cars will be allowed to proceed when the bridge is lowered